Figure 8.3 shows a plot of simulated amplitude-response
measurements at 10 frequencies equally spread out between 100 Hz and 3
kHz on a log frequency scale. The ``measurements'' are indicated by
circles. Each circle plots, for example, the output amplitude divided
by the input amplitude for a sinusoidal input signal at that frequency
[452]. These ten data points are then extended to dc and half
the sampling rate, interpolated, and resampled to a uniform frequency
grid (solid line in Fig.8.3), as needed for FFT processing.
The details of these computations are listed in Fig.8.4. We
will fit a four-pole, one-zero, digital-filterfrequency-response to
these data.9.14